This invention relates to polymerization apparatus for manufacturing synthetic condensation polymers. More particularly it concerns a flashing reactor to be used with continuous polymerizers for nylon polymer of high capacity.
Flashing reactors or flashers as they are usually called consist of a series of sections of pipe of successively increased diameter surrounded by a heating jacket such as described by Heckert in U.S. Pat. No. 2,689,839 or by Iwasyk et al in U.S. Pat. No. 3,789,584. Such single pipe flashers when used with high capacity continuous polymerizers suffer from operational deficiencies which include polymer gelation, high levels of entrained nylon aerosols due to high steam velocities needed to reduce the degree of polymer gelation in the larger pipe sizes, and lower relative viscosity (RV) for the polymer exiting the flasher as a result of short residence time due to high steam velocities. Polymer gelation develops when the flasher pipe diameter gets above about 31/2" Schedule 40 I.P.S. The polymer is not symmetrically distributed about the pipe wall but, due in part to gravity action, tends to become concentrated at the bottom of the pipe. If high velocity steam is used to attempt to hold and distribute the polymer more evenly about the pipe wall, there is an increase in the amount of polymer which becomes entrained in the steam as aerosols and the RV of the polymer decreases because of shorter residence time in the flasher. The increase in aerosols enhances the buildup of polymer deposits in the vent system of the finisher to which the flasher discharge pipe is connected. This leads to more frequent shutdown of the whole system for vent cleaning.